Imaging diagnostics by combining contrast agents

ABSTRACT

The present invention relates to the use of a combination of several contrast agents having different properties with respect to imaging representation.

The present invention relates to the use of a combination of severalcontrast agents having different imaging properties.

Chronic diseases are an important field of application for imagingdiagnostics. The two most frequent chronic diseases, cardiovasculardiseases and tumour diseases, alone account for the greater part of the800 million imaging diagnoses which are carried out every yearworldwide. The majority of examinations are ultrasonic examinations,X-ray examinations, such as CT and MRI examinations, but alsonucleomedical and optical methods are often used. For all of theseexamination methods, contrast agents are clinically available. Contrastagents provide specific information determined by their pharmacokineticand pharmacodynamic properties. However, imaging examination alone oftenallows only for little diagnostic information. Due to this reason, it isoften necessary to carry out various examinations with the same modalityand different contrast agents or to carry out different examinationswith different modalities, in order to allow a reliable diagnosis. Thisprocedure involves high costs and strain/stress for the patient.Furthermore, this approach is time-consuming and, the beginning of anecessary therapy is often delayed due to the fact that severaldiagnostic examinations are required. A further disadvantage is theassignment of diagnostic signals from different imaging examinations.Very often, it is not possible to correlate suspect lesions of oneexamination to the lesions detected in another examination, whichconsiderably complicates the diagnosis for the physician. The necessityto carry out different diagnostic examinations in order to establish areliable diagnosis can be illustrated by the imaging diagnostics oftumours, particularly the imaging diagnostics of breast cancer.

Breast cancer is one of the most frequent tumours and the most frequenttumour disease with women. Improved early diagnosis, such as screeningmammogram, and complex treatment protocols allowed a decrease inmortality over the last years. Nonetheless, a great number of breastcancer cases are only detected at a late stage. Hence, the earlydiagnosis of tumours is a great challenge. This is particularlyimportant as the growth of small tumours is limited to the organ so thatthere is hope to remove the tumour completely and to conserve the organif tumours are detected in early stages. Medical methods available up topresent meet this requirement only inadequately. Hence, it is importantto provide improved methods of early and reliable diagnosis.

Today, the physician can use various diagnostic methods with the imagingtechniques playing a major role. Among the imaging techniques,ultrasonic diagnosis, CT, MRI and nucleomedical techniques, such as PETand SPECT, are the most relevant techniques. With unclear diagnosticfindings, the aim is to take tissue samples from suspect lesions and toprepare and assess these samples histopathologically.

MRI examination of the female breast has very high sensitivity incomparison to other imaging modalities. Due to this modality, it ispossible to detect different forms of breast cancer at an early stage. Aparticular advantage of MRI is the fact that imaging examination is notcomplicated in a significant way by non-tumerous tissue alterations,such as e.g. surgical cicatrices, tissue alterations by radiologicaltreatment, prostheses or mastopathically altered glandular tissue. Dueto these characteristics, MRI has meanwhile found a large range ofapplications.

The high sensitivity of MRI of the breast is, however, associated withlow specificity. Low specificity implies that almost all malignanttumours are detected but that, at the same time, many foci which, in thecourse of subsequent examinations, are found to be harmless, arerepresented as malignant tumours. The reason for this is that MRI usescontrast agents which improve the method to a degree that allows to showeven minor irregularities in the breast tissue to be examined. Thesecontrast agents are not appropriate to make a satisfactory distinctionbetween benign and malignant lesions. As a consequence of the diagnosticresults, the physician has to initiate further examinations which are toassess the presumptive diagnostic findings in greater detail. On the onehand, further imaging methods are applied, on the other hand, it ispossible to make an MRI-based biopsy of the suspect tissue and establishan exact diagnosis by histological examination. The fact that this is amethod of high technical standard involving high costs is one of thereasons why MRI imaging has not yet been established as standard methodfor breast cancer diagnosis. As to clinical application of CT, thesituation is similar. CT also plays a major role in tumour diagnosis.For example, the CT-contrast agent Ultravist® is used for imaging CTdiagnosis of liver tumours. This method also shows minor specificitywith respect to the contrast agents based diagnosis. Thus, it is acentral task to improve the specificity of diagnostic imaging in orderto make it widely applicable.

One possibility to improve the specificity of information provided by animaging modality is to use improved signal altering or signal modulatingcontrast agents. Today, contrast agents are clinically available formost of the imaging methods. These contrast agents are selected in sucha way that, on the one hand, their application is acceptable with humansand that, on the other hand, they can interact with the physical signalof the relevant examination modality in a very specific manner. Mostempirical data regarding the application of contrast agents relate toX-ray-based CT examination methods. Diagnostic radiology uses contrastagents which attenuate the X-rays. These are, amongst others, substanceswith a great number of elements having high electron density, such asiodine. These contrast agents can be applied in a variety of ways inhumans, however, the most frequent applications are applications inwhich the contrast agents are introduced by bolus injection into theblood circulation. By applying contrast agents in this way, it ispossible to make the blood flow in a specific organ visible for theduration of the examination. This application form of contrast agentsallows to obtain important information on the anatomy, morphology andfunction of specific organs. Thus, it is possible to obtain informationon the condition of a blood vessel by detecting a contrast agent in thisblood vessel and by visualizing the vessel lumen. Existing constrictionsof the coronary arteries can be made visible by coronary angiographywithout difficulties, thus, leading to the diagnosis of coronarystenosis. Another parameter providing significant diagnostic data is thevelocity with which the contrast agent applied flows into the organ.Thus, it is possible to draw conclusions with respect to the bloodcirculation within a particular organ. The application of contrastagents is as important in MRI as it is in radiodiagnostics. ForX-ray-based examinations as well as for MRI examinations, a great numberof different contrast agents is available to the physician. However, allof these contrast agents are optimised for specific applicationpurposes. Extracellular contrast agents (ECCM) play a major role in thedetection of tissue lesions, such as tumours, diseases of the centralnervous system (CNS) and diseases of the cardio-vascular system. Thesecontrast agents are optimised in such a way that their concentration inthe blood is rapidly reduced from a maximum concentration to a minimumconcentration within very few minutes after their application (alphaslope, blood kinetics). Furthermore, they are characterised in that theyhave plasma protein binding of less than 90%, preferably of less than70%. ECCM can easily be selected from a series of different contrastagents by in-vivo imaging studies in animals or human. In these in-vivostudies a fast decline of the imaging signal over the target lesion orreference regions indicates a characteristic of ECCM. Due to their smallmolecular size and the incomplete binding to plasma proteins, theyeasily pass the capillary barrier. Another significant property of theECCM is the lack of interaction with biological structures. ECCM do notbind to specific structures in the lesion to be examined and are notaltered by these structures. Due to these properties, they can pass thecapillary barriers in both directions and, thus, they are capable ofdemarcating suspect lesions from the surrounding healthy tissue. Thisprocess is known as extravasation and occurs also in an intact capillarysystem, though with clearly reduced velocity. In particular with tumourdiseases, diseases of the central nervous system and diseases of thecardio-vascular system, the capillary barrier is defect and ECCM leakageoccurs preferably at these sites. Extravasation of the ECCM results in asignal increase in the lesion in comparison to the healthy surroundings.Within the first minutes after injection of an ECCM, signal increases ofup to 100% can be observed. This first phase of the extravasationprocess is also known as wash-in. This phase can be followed by a rapidbut often incomplete washout phase. The signal in the lesions can beinferior to the signal in the surroundings, as, due to the disturbedbarrier function, the wash-out process in the lesion can occur fasterthan in the healthy tissue where the intact barrier reduces the velocityof back flow. Back flow is however always caused by fast decrease of theECCM concentration in the blood. This is a characteristic property ofthe ECCM used according to the invention. Fast elimination from bloodcirculation requires incomplete and loose binding of plasma protein andis ensured by renal and/or hepatic elimination capacity, in contrast toECCM, lesion-specific contrast agents (LSCM) used according to theinvention are characterised in that they can interact with a specifictarget structure in the organism or are altered by said specificstructures in such a way that they can be visualised in by an imagingtechnique as a consequence of the interaction or alteration. A furtherproperty by which they can be distinguished from ECCM is their longerretention in blood circulation. This property can be achieved, forexample, by ensuring that the relevant LSCM are characterised by astronger plasma protein binding of more than 90%. The characteristicproperties of LSCM can easily be detected by in-vivo imaging studies inanimals or human. A continuous accumulation in the target lesionindicates a LSCM.

The most important ECCM in MRI is gadolinium-DTPA (Gd-DTPA). Gd-DTPA isa paramagnetic substance which leads to a reduction of the T1 relaxationtime of the surrounding tissue. It is a substance with low molecularweight, which does not interact with structures of the organism and isnot altered by these. Due to this property, it is capable of leaving thecapillary system even if the capillary barrier is intact and vascularpermeability is normal. Having left the capillary system, Gd-DTPAspreads in the extravasal space. Many diseases, such as e.g. tumourdiseases, inflammatory organ alterations or tissue injuries due toapoplexia result in damage of the capillary barrier. If patientssuffering form such diseases are subjected to MRI examinations with thecontrast agent Gd-DTPA, the contrast agent extravasates to an increaseddegree in areas where the capillary barrier is damaged. Theconcentration in the tissue is increased particularly in these areas,which is noticeable by an increased signal in the MRI image. This effectis followed by an increased back diffusion also known as wash-outphenomenon. This characteristic behaviour, which is also known as“wash-in/wash-out” phenomenon, can be used in MRI diagnosis in variousways, e.g. for the detection of tumours with high scanning speeds duringthe injection of contrast agent in MRI. In particular the imagingdiagnostics of suspect tissue alterations of the female breast provedthat the “wash-in/wash-out” phenomenon allows to detect probably allmalignant breast lesions above a certain size. The method, however, alsohas a great disadvantage. In addition to the existing malignant tumours,many benign foci are detected. These are various benign tissuealterations of different kinds which bear no risk for the patients.

So far, no method is known which would enhance the specificity of highlysensitive imaging methods in a satisfactory way.

A possibility to enhance the specificity of imaging examination methodsconsists in carrying out different contrast agent-based examinations. Inthe literature, methods are known wherein the suspect disease lesionswere characterised by subsequently using two different MRI contrastagents. For this monomodal method, the examination was carried out intwo steps. First, an LSCM was applied. Due to the long retention period,the concentration of an ECGM could only be examined by a delayed secondexamination. This approach has the decisive disadvantage that bycarrying out the examinations separately, an overlap of the two signalsis possible only in a limited way. Thus, the method known fromliterature loses some of its sensitivity and specificity and offers noadvantage [Marcarini L. et. al; Radiol. Med. (2006) 111: 1087-1102].

Surprisingly, it was found that the use of ECCM in combination with atleast one further imaging contrast agent or signalling substance whichtends to concentrate specifically in the disease lesion (lesion-specificcontrast agent/LSCM) is a completely new imaging method having amarkedly higher specificity than the application of an ECCM alone. Thecombination of the invention is characterised in that the ECCM and theLSCM are applied at the same time or the LSCM is applied with a shorttime delay of 30 minutes maximum, preferably of 20 minutes maximum, mostpreferably of 10 minutes maximum after the application of the ECCM.Thus, the method of the invention allows to interpolate the differentimaging signals and to achieve a lesion diagnosis of high sensitivityand high specificity. Interpolation means that, in a given examinationarea/region, at least two signals differing from each other can be/arerelated in space and in time. Thus, the invention resolves thedisadvantages of the state of the art—with diagnostic methods beingcarried out independently from one another—by combining ECCM and LSCMwhich allows a useful interpolation of the different imaging signals.Diagnostic methods being carried out independently from one anothermeans, that the patient is moved from the examination table in betweenthe diagnostic methods. The ECCM is used to detect the lesions, whereasthe LSCM is used to characterise the lesions. By using this method, thenumber of false positive diagnostic findings can be decreasedsignificantly and physician as well as patient can be spared unnecessaryexaminations. Unexpectedly, the present invention provides for anincreased diagnosis sensitivity and specificity in comparison with thestate of the art, wherein images from independent examinations aremerely spatially overlaid. The present invention furthermore allows foradjusting examination parameters such as the spatial area which lieswithin the focus of the diagnostic apparatus or the irradiationintensity as a consequence to the result obtained by one of the contrastagents, thereby enhancing the result obtained with the other contrastagent. Used in combination according to the invention, ECCM and LSCM arecontrast agents with complementary action properties.

Thus, subject matter of the present invention is an extracellularcontrast agent (ECCM) for the diagnosis of lesions incombination/conjunction with a lesion-specific contrast agent (LSCM).According to the invention, the individual contrast agents of thecombination of ECCM and LSCM may be imaging contrast agents for a singlesynthetic imaging method (monomodal) or multiple synthetic imagingmethods (polymodal).

The combination of ECCM and LSCM according to the invention envisages afixed time sequence for the application of the individual substances. Inthe case of the monomodal technique, the ECCM is administered first andthe LSCM is administered subsequently. The LSCM is administered at theearliest when the ECCM level in the blood has reached a level thatallows detecting the LSCM.

Thus, subject matter of the present invention is also an extracellularcontrast agent (ECCM) for the diagnosis of lesions, wherein, in the caseof the monomodal technique, the ECCM is provided for in a manner suitedfor the intended use for administration as first contrast agent and theLSCM is provided for in a manner suited for the intended use as secondcontrast agent to be administered after the ECCM level in the blood hasdeclined to a level that allows the detection of the ECCM. In the caseof the polymodal technique, the contrast agents may be provided for in amanner suited for the intended use in such a way that they can beadministered at the same point in time. In the case of the polymodaltechnique, they may, however, be provided for in a manner suited for theintended use in such a way that the LSCM is prepared for administrationas first contrast agent and the ECCM for administration as secondcontrast agent. This approach surprisingly provides the possibility toinvestigate the distribution of the disease in the whole body as thefirst step, and to perform detailed characterisation of the suspiciouslesions with ECCM as the second step.

Preferably, in a polymodal technique, the LSCM is administered as firstcontrast agent and the ECCM is administered as second contrast agent,where the image registration of the LSCM is performed first, and theimage registration for the ECCM is performed second. As an example, inthe combination of 18F-Fluordeoxyglucose (FDG) as LSCM for PET imagingwith Ultravist® as ECCM for CT imaging for a combined PET/CT imaging ofcancer, after administration of FDG and subsequent administration ofUltravist®, the PET exam with image registration of the LSCM isperformed. As FDG is accumulated not only in e.g. cancer cells, but alsoin a variety of normal ceils (e.g. brain) and cells affected by otherdisease (e.g. inflammation), the subsequent CT imaging for imageregistration of the ECCM is performed only in the regions with increasedFDG uptake to allow a high-resolution imaging with a slice collimationof 2 mm or less, preferably of 1 mm or less in CT for detection ofsubtle morphologic signs, e.g. of cancer.

Preferably, the combination of the invention is, however, used in such away that the ECCM is administered first in order to detect suspectlesions in the relevant organs. The LSCM is then used in order toprovide information with respect to the kind of lesions based on itsconcentration in said lesions.

In the case of the polymodal technique, both contrast agents can beadministered Sequentially—like in the monomodal technique—andsimultaneously. Thus, subject matter of the present invention is anextracellular contrast agent (ECCM) for the diagnosis of lesions incombination with LSCM, wherein in the case of the polymodal method

-   -   either the ECCM is prepared for administration as first contrast        agent and the LSCM is prepared as second contrast agent to be        administered after the level of ECCM in the blood has declined        to a level that allows the detection of the ECCM, or    -   the ECCM and the LSCM are prepared for simultaneous        administration.

The contrast agents may also be prepared in such a way that the LSCM isprepared for administration as first contrast agent and the ECCM foradministration as second contrast agent. Subject matter of the presentinvention is also a method for the diagnosis of lesions, wherein anextracellular contrast agent (ECCM) is administered incombination/conjunction with a lesion-specific contrast agent (LSCM)and, preferably, the imaging signals are interpolated immediately.

The ECCM of the invention are signaling and signal-modulating substancesfor synthetic imaging techniques which, after having been applied tohumans, rapidly reach a high peak concentration in the blood due to thebolus-like injection which is normally used and the high concentrationof said ECCM rapidly declines from this high level by their spreadinginto the whole organism (alpha slope, elimination kinetics). In general,this process is terminated within 5 to 10 minutes after application. Ingeneral, after 5 to 10 minutes after application the substance levels incirculation are below a level allowing imaging detection. Renal andhepatitic elimination, or a combination of both, is decisive for furtherclearance of substance levels from the circulation. For fast eliminationfrom blood circulation, the imaging substances must be of smallmolecular size. The elimination of substances with a molecular weight ofmore than 2,000 to 5,000 is significantly slower compared to theelimination of substances with a molecular weight of up to 1,000 g/mol.Hence, the ECCM of the invention have a molecule size of less than 2,000g/mol, preferably of less than 1,000 g/mol. Another important propertyof the ECCM is their hydrophilicity. Substances having highhydrophilicity are eliminated fast. The elimination of substances havinglow hydrophilicity is significantly delayed. Hydrophilicity of the EGCMof the invention is characterised by a distribution coefficient of logP<−2 (less than minus two in n-butanol/water), preferably by adistribution coefficient of log P<−3 (less than minus three inbutanol/water).

ECCM of the invention are contrast agents for MRI, X-ray-basedtechniques such as CT, optical techniques, optoacoustical techniques,ultrasonic techniques and nucleomedical techniques. They arecharacterised in that they do not interact with structures of theorganism after injection and in that they are not altered in theirsignalling property by interaction with structures of the organism.Their movement is determined by the velocity of distribution andelimination. After reaching the maximum concentration in the blood, theprocess of distribution is completed and substance levels which are nolonger sufficient for imaging are reached preferably after 10 minutes.Hence, 30 minutes after injection at the latest, preferably 20 minutesafter injection, most preferably after 10 minutes after injection, theconcentration of the contrast agents of the invention in the bloodcirculation is reduced to a degree that the LSCM can be applied.

ECCM are particularly preferred which exhibit a blood concentration thatis reduced to a level allowing administration of the LSCM after 30minutes at the latest, particularly preferred after 10 to 15 minutes.Animal imaging studies can be applied to discriminate between ECCM andLSCM. A fast decline of the imaging signal over the target lesion orreference region is a characteristic of ECCM, whereas LSCM exhibits acontinuous accumulation in the target lesion over more than 30 to 60 minafter application.

Thus, in the present invention, the ECCM and LSCM are defined by theirdifferent target lesion elimination times. Hereby, the absoluteelimination time of each contrast agent from the target lesion is not ofparticular significance, but rather the relative elimination times ofthe contrast agents to be used as ECCM/LSCM pair. This means that theECCM is eliminated in 20% of the time or less, more preferably in 10% ofthe time or less, with respect to the elimination time from the targetlesion of the LSCM, wherein preferably, the time difference between theelimination of the ECCM and the LSCM to a level of 10% of the maximumconcentration of ECCM and LSCM in the target lesion is at least 20 min,more preferably at least 30 minutes. Consequently, many contrast agentsmay be used both as LSCM or ECCM, depending whether the second contrastagent which is used in conjunction therewith has a slower or more rapidelimination. Hereby, the tissue type which is comprised by the area ofinterest will have to be accounted for, as several contrast agents showdifferent elimination times in different tissue types. In general, aperson skilled in the art will recognize combinations of contrast agentswhich represent appropriate ECCM/LSCM pairs for a given application anda given tissue type, as the elimination behaviour of most contrastagents has already been described in great detail. In some caseshowever, a simple experiment will have to be conducted in which theelimination behaviour of a contrast agent in a certain tissue type ismonitored. The skilled person, such as a radiologist, is trained tocarry out such experiments routinely. In this context, the term“eliminated” or “elimination” means that the level of contrast agent ina given area of diagnostic interest has reached a value of 10% or lessof the maximum level after injection.

ECCM are substances, contrast agents or effector molecules, preferablyselected from the group comprising:

-   -   metal complexes with paramagnetic metals,    -   superparamagnetic, ferromagnetic or ferrimagnetic iron oxide        particles with polymeric protective coating,    -   complex-bound, chelator-bound and covalently bound radioactive        nuclides,    -   gas-filled, polymeric microparticles or microvesicles,—gas        precursors,    -   organic, metallo-organic or anorganic chromophores or        fluorophores,    -   structures which biosynthetically form organic chromophores or        fluorophores,    -   structures with a high absorption cross section for X-rays,    -   structures having an effect on electric impedance.

Subject matter of the invention is the use of ECCM containingparamagnetic metal ions. Preferred paramagnetic metal ions are ions oftransitional metals and lanthanoid metals (e.g. metals having the atomicnumbers 6-9, 21-29, 42, 43, 44, or 57-71), in particular ions of Cr, V,Mn, Fe, Co, Ni, Cu, La, Ce1 Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,Yb and Lu. Mn, Cr, Fe, Gd and Dy are preferred. Gd is particularlypreferred.

These ions are stably bound or complexed by complex forming structuresor groups of chelators. The latter are macro-cyclic or open-chainpolyaminocarboxylic acids. Macro-cyclic chelator groups are preferablytetraazacyclododecane chelators, such as1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA);1,4,7,10-tetraazacyclododecane-N,N′,N″-triacetic acid (DO3A);1-Oxa-4,7,10-triazacyciododecane-N,N′,N″-tretraacetic acid (OTTA);trans(1,2)-cyclohexanodiethylentriamine pentaacetic acid (CDTPA) andanalogues thereof, or ethylenamine chelator groups, such asN,N,N′,N″,N″-diethylenetriamine pentaacetic acid (DTPA),ethyleneediamine tetraacetic acid (EDTA), as well as their chemicalsubstitution derivatives at the ethylene and/or acetic acid residues.Further derivatives are DTPA-BMA, DPDP, TMT and HPDO3A, gadubotrol(Gadovist®), gadopentetatic acid/dimeglumine salt (Magnevist®),gadobenic acid (Multihance®), gadodiamide (Omniscan), gadoxeticacid/disodium salt (Primovist®; Gd-EOB-DTPA), and gadoteridol(Prohance®).

Gadubotrol (Gadovist®), gadopentetatic acid/dimeglumine salt(Magnevist®), gadobenic acid (Multihance®), gadodiamide (Omniscan),gadoxetic acid/disodium salt (Primovist®; Gd-EOB-DTPA), and gadoteridol(Prohance®) are particularly preferred.

Subject matter of the invention are ECCM containing superparamagneticiron oxide particles. These are biocompatible and acceptable due to thestabilizing protective coating. The iron oxide particles with protectivecoating have a diameter of 20-500 nm, preferably of 20-200 nm.Protective coatings consists of polymers, in particular polysaccharidessuch as dextran. SPIOs, USPIOs, MIONs are particularly preferred.

Subject matter of the invention are ECCM containing chromophores orfluorophores. Chromophores or fluorophores are structures which have anextended system of delocalized electrons, which absorb and fluorescewithin a spectral range of 300-1400 nm. Chromophores or fluorophoreswith an absorption and/or emission maximum of 400-600 nm (visiblefluororescence) as well as an absorption and/or emission maximum of650-1000 nm, in particular 700-900 nm (near-infrared fluorescence).

Chromophores or fluorophores with visible fluorescence are NBD,fluoresceins, rhodamines, tetrapyrroles (e.g. porphyrines,protoporphyrine SX), pyrilium dyes, Thai pyrilium dyes, croconium dyes,squarylium dyes, benzophenoxazinium dyes, benzothiaphenothiazinium dyes,anthraquinones, naphthoquinones, phthaloylacridones, azo dyes, diazodyes and complexes of the lanthanoid metals La, Ce, Pr, Nd1 Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, Eu, Tb, Yb with macrocyclic oropen-chain polyaminocarboxylic acids or polyaminocarboxylic acidsphosphoric acids. Fluorescein is particularly preferred.

Chromophores or fluorophores with near-infrared fluorescence arepolymethin dyes, particularly cyanine dyes, merocyanines,phthalocyanines, naphthalocyanines, triphenylmethines, croconium dyes,squary[upsilon]urn dyes. Indocyanines, in particular indocyanine green,DODCl1 DTDCl, DOTCl and DDTCl and derivatives are preferred. Indocyaninegreen (ICG, CardioGreen, IC Green, DiagnoGreen) is particularlypreferred.

Examples can be found in “Topics in Applied Chemistry: Infraredabsorbing dyes” Ed. M. Matsuoka, Plenum, N.Y. 1990, “Topics in AppliedChemistry: The Chemistry and Application of Dyes”, Waring et al.,Plenum, N.Y., 1990, “Handbook of Fluorescent Probes and ResearchChemicals” Haugland, Molecular Probes Inc, 1996, DE-A-4445065,DE-A-4326466, JP-A-3/228046, Narayanan et al., J. Org. Chem. 60:2391-2395 (1995), Lipowska et al., Heterocyclic Comm. 1: 427-430 (1995),Fabian et al., Chem. Rev. 92: 1197 (1992), WO96/23525, Strekowska etal., J. Org. Chem. 57: 4578-4580 (1992), WO (Axis) and WO96/17628.

Subject matter of the invention are also ECCM comprising particulate orvesicular polymers which contain, transport and/or release air orfluorinated gases (e.g. SFe or perfluorinated alkanes with 1-6 C-atomsor other gases as described in WO97/29783). Echovist®, Levovist,Sonavist®, Sonuvue and Optison® are particularly appropriate.

Subject matter of the invention are ECCM containing radionuclides.Radionuclides are non-metal nuclides as well as metal nuclides for thetechniques of SPECT (single photon emission computed tomography) or PET(positron emission tomography), respectively.

Non-metal nuclides are covalently bound to carbons of chemicalstructures. A particularly preferred non-metal nuclide is radioactiveiodine (SPECT: ¹²⁵I, ¹²³I, ¹³¹I, PET: ¹²⁴I) or carbon ¹¹C (PET).

Metal radionuclides are preferably ⁹⁰Y, ^(99m)Tc, ¹¹¹Sn, ⁴⁷Sc, ⁶⁷Ga,⁵¹Cr, ^(177m)Sn, ⁶⁷Cu, ¹⁶⁷Tm, ⁹⁷Ru, ¹⁸⁸Re, ¹⁷⁷Lu, ¹⁹⁹Au, ²⁰³Pb and ¹⁴¹Ce(for SPECT) and ⁸⁶Y, ^(94m)Tc, ^(11Om)In, ⁶⁸Ga, ⁶⁴Cu (for PET). Theseare bound by complex forming structures or radioactive chelators.

Chelators for metal radionuclides are structures with donor atoms, suchas N, S, O, which bind the metals in appropriate configuration in spaceand form a cyclical metal complex or chelates. These are in particularISI3S, N2S2 systems on the basis of aminoalkyl, thioalkyl,aminocarbonyl, thiocarbonyl structure elements (Kirk-Othmer Encyclopediaof Chemical Technology, Vol. 5, 339-368).

Chelators on the basis of N3S and N2S2 are described e.g. in U.S. Pat.Nos. 4,444,690; 4,670,545; 4,673,562; 4,897,255; 4,965,392; 4,980,147;4,988,496; 5,021,556 and 5,075,099, WO92/08494. Furthermore,representative chelators are described in U.S. Pat. No. 5,559,214 A, WO95/26754, WO 94/08624, WO 94/09056, WO 94/29333, WO 94/08624, WO94/08629 A1, WO 94/13327 A1 and WO 94/12216 A1; WO89/00557, U.S. Pat.Nos. 4,647,447; 5,367,080; 5,364,613. Chelates are also modifiedproteins which bind e.g. ^(99m)Tc (U.S. Pat. No. 5,078,985).

Chelate structures are selected from mycrocyclic or open-chain aminocarboxylic acids. Macrocyclic chelator groups are preferablytetraazacyclododecane chelators, such as1,4,7,10-Tetraazacyciododecane-N,N′,N″,N′″-tetraacetic acid (DOTA);1,4,7,10-tetraazacyclododecane-N,N′,N″-triacetic acid (DO3A);1-Oxa-4,7,10-triazacyclododecane-N,N′,N″-triacetic acid (OTTA) anddibenzo[18]crown-6, (CH₃)₆-[14]-4,11]-dien-N₄, and (2.2.2-cryptate).Open-chain amino carboxylic acids are, for example,trans(1,2)-cyclohexanodiethylentriamine pentaacetic acid (CDTPA) andanalogues thereof, N,N,N′,N″,N″-diethylentriamine pentaacetic acid(DTPA), ethylene diamine tetraacetic acid (EDTA),N-(2-hydroxy)-ethylene-diamine triacetic acid, nitrilotriacetic acid,N,N-Di-(2-hydroxyethyl)glycine, ethylenebis-(hydroxyphenylglycine) andderivatives thereof by chemical substitution at the ethylene and/oracetic acid residues. Further derivatives are DTPA-BMA, DPDP, TMT andHPDO3A.

Moreover, chelate structures are selected from the substance classes ofpolyphospates, such as sodium polyphosphate and hexametaphosphoric acid;1,3-diketones, e.g. acetylacetone, trifluoracetylacetone,thenoyltrifluoroacetone; hydroxycarboxy[upsilon]c acids, e.g. lacticacid, citric acid, gluconic acid and 5-sulfosalicylic acid, polyamines,e.g. ethylenediamine, diethylenetriamine, triethylenetetraamine,triaminotriethylamine; amino alcohols, e.g. triethanolamine andN-{2-hydroxyethyl)-ethylenediamine; aromatic heterocyclic bases, e.g.2,2′-diimidazole, picolinamine, dipicolinamine, 1,10-phenanthrolin;phenols, e.g. salicylaldehyde, disulfopyrocatechol; aminophenois, e.g.8-hydroxyquinoline oximesuifonic acid; oximes, e.g. dimethylglyoxime,salicylaldoxime; peptides with chelating end groups, e.g. polycystein,polyhistidine, polyasparaginic acid, polyglutamine acid,glycine-glycine-cystein or combinations of such amino acids; Schiff'sbases, e.g. disalicylaldehyde, 1,2-propylendiimine; tetrapyrroles, e.g.porphyrins, tetraphenylporphyrins, benzoporphyrins, chlorines,tetraphenylchlorines, benzochlorines, bacteriochlorines, pheophorbides;purpurinimides, expanded tetra- and pentapyrroles (texaphyrines);sulphur compounds, e.g. toluene-dithiole, meso-2,3-dimercaptosuccinicacid, dimercaptopropanol, thioglycolic acid, sodiumdiethyldithiocarbamate, dithizone, diethyldithiophosphoric acid,thiourea; phosphonic acids, e.g. nitrilotrimethylene phophonic acid,ethylene diamine-tetra(methylene phosphonic acid),hydroxyethylidendiphosphonic acid or combinations of 2 or more of thestructures mentioned.

Complex forming substances for ^(99m)Tc are, furthermore,^(99m)Tc(I)(H₂O)₃(CO)₃ ⁺, from which the ^(99m)Tc-tricarbonyl complexwith amino carboxylic acids or other chelating donor atoms is formed.

Subject matter of the invention are ECCM which exhibit X-ray absorption,in particular triiodized aromatic hydrocarbons and complexes withlanthanoid ions La, Ce, Pr, Nd, Pm1 Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,and Lu, Eu, Tb, Yb, preferably Gd, Tb, Dy, Ho, and structures containingtriiodized aromatic hydrocarbons and complexes with tanthanoid ions andiodixanol (Visipaque®), iopromid (Ultravist®), ioxaglinic acid(Hexabrix®), iomeprol (Imeron®), iopamidol, iotrolan (Isovist), iosurcal(Melitrast), iohexol (Omnipaque®), amidotrizoic acid (Peritrast),meglumine ioxithalamate (Telebrix), iobitridol (Xenetix®) andgadolinium-DTPA. Iodixanol (Visipaque®), iopromid (Ultravist®),ioxaglinic acid (Hexabrix®), iomeprol (Imeron®), iopamidoi, iotrolan(Isovist), iosurcal (Melitrast), iohexol (Omnipaque®), amidotrizoic acid(Peritrast), meglumine ioxithalamate (Telebrix), iobitridol (Xenetix®),and gadolinium-DTPA are preferred.

In a particularly preferred embodiment, the ECCM is gadolinium DTPA.

The lesion-specific contrast agents (LSCM) according to the inventionare signalling or signal-modulating substances for image synthesisprocedures characterised in that they interact with structures in theorganism or they are modified by structures in the organism as to theirsignalling properties and they provide additional imaging informationwhich improve the specificity of the method. Said additional informationcan be information as to anatomy, morphology, function, metabolism ormolecular expression of specific factors. The substances according tothe invention are characterised in that after application in the lesiontissue they concentrate continuously and, in contrast to ECCM, remain inthe lesion over a longer period of time during examination and do notexhibit any wash-in/wash-out phenomenon. The concentration can beachieved by different mechanisms which aim at preventing fastelimination from the blood circulation. The lesion-specific agentsaccording to the invention can bind to specific binding sites,concentrate in cell membranes, be activated by enzyme activity, bind toextracellular proteins, absorbed by cells of the RES or enter cells ofthe lesion tissue. These substances are characterised in that theirelimination from the blood circulation takes clearly more time incomparison to the ECCM. Due to said longer period of time, the agentsare capable of accumulating in the suspect lesions by the mechanismsmentioned and stay there. Preferably after 15 minutes to 24 hours,particularly preferred after 15 minutes to 3 hours, the process leads todemarcation of the disease lesion from the surrounding healthy tissue,which can be diagnostically measured. With this demarcation which can bemeasured diagnostically, it is of no importance whether the LSCMconcentrates in the tissue of the disease lesion or in the surroundinghealthy tissue.

Preferably, the LSCM accumulates in the lesion after 10 minutes andstays there for at least one hour, whereas particularly preferred theconcentration of the LSCM in the lesion continuously increases withinthe period of 10 minutes to 60 minutes.

LSCM according to the invention are contrasting agents for the MRI1 forX-ray-based techniques such as e.g. CT1 for optical techniques, foroptoaccoustic techniques, for ultrasonic techniques and for nuclearmedicine techniques.

The LSCM are active substances, contrasting agents or effectormolecules, selected from the following group, comprising:

-   -   metal complexes with paramagnetic metals,    -   superparamagnetic, ferromagnetic or ferrimagnetic iron oxide        particles with polymeric protective coatings,    -   complex-bound, chelator-bound and covalently bound        radionuclides,    -   gas-filled, polymeric microparticles or -vesicles,    -   gas precursors,    -   organic, metal-organic or inorganic chromophores and        fluorophores,    -   structures biosynthetically forming organic chromophores or        fluorophores,    -   structures with high absorption cross section for X-rays,    -   structures influencing electric impedance.

Use of LSCM containing paramagnetic metal ions are subject matter of theinvention. Preferred paramagnetic metal ions are ions of thetransmission and lanthanoid metals (e.g. metals of atom numbers 6-9,21-29, 42, 43, 44, or 57-71), in particular ions of Cr, V, Mn, Fe, Co,Ni, Cu, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.Mn, Cr, Fe, Gd and Dy are preferred. Gd is particularly preferred.

These ions are stably bound or complexed by complex forming structuresor chelator groups. The latter are polyaminocarboxylic acids withmacrocyclic or open-chain structure. Groups of macrocyclic chelatoragents are preferably tetraazacyclododecane chelates, such as1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA);1,4,7,10-tetraazacyclododecan-N,N′,N″-triacetic acid (DO3A);1-Oxa-4,7,10-triazacyclododecane-N,N′,N″-triacetic acid (OTTA);trans(1,2)-cyclohexanodiethylentriamine pentaacetic acid (CDTPA) andanalogues thereof, or ethylenamine chelator groups, such asN,N,N′,N″,N″-diethylenetriamine pentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), as well as their derivatives by chemicalsubstitution at the ethylene and/or acetic acid residues. Furtherderivatives are DTPA-BMA, DPDP, TMT and HPDO3A.

Gadofosveset (Vasovist®), Gadofluorine, Gadofluorine-M and Gadomer-17are particularly preferred.

LSCM containing superparamagnetic iron oxide particles are subjectmatter of the invention. These are biocompatible and acceptable due totheir stabilising protective coatings. Specifically, the iron oxideparticles with protective coating have a diameter of 20 to 500 nm,preferably 20-200 nm. Protective coatings consist of polymers, inparticular polysaccharides such as dextran.

SPIOs, USPIOs1 MIONs, Ferucarbutran (Resovist®, Supravist®) areparticularly preferred.

LSCM containing chromophores or fluorophores are subject matter of theinvention. Chromophores or fluorophores are structures with an elaboratesystem of delocalised electrons, which absorb and fluoresce within thespectral region of 300 to 1400 nm. Chromophores or fluorophores with anabsorption and/or emission maximum of 400 to 600 nm {visiblefluorescence) as well as an absorption and/or emission maximum of 650 to1000 nm, in particular 700 to 900 nm (near-infrared fluorescence) arepreferred.

Chromophores or fluorophores with visible fluorescence are NBD1Fluorescein, rhodamines, tetrapyrroles (e.g. porphyrins, protoporphyrinIX)1 pyrilium dyes, thaipyrilium dyes, croconium dyes, squarilium dyes,benzophenoxazinium dyes, benzothiaphenothiazinium dyes, anthraquinones,napthoquinones, phthaloylacridones, azo dyes, diazo dyes, as well ascomplexes of the lanthanoide metals La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, and Lu1 Eu1 Tb, Yb with macrocyclic or open-chainpolyaminocarboxylic acid or polyaminocarboxylic acids phosphoric acids.

Chromophores or fluorophores with near-infrared fluorescence arepolymethin dyes, in particular cyanin dyes, merocyanins, phthalocyanins,naphthalocyanins, triphenyl-methins, croconium dyes, squarilium dyes.Examples can be found in “Topics in Applied Chemistry: Infraredabsorbing dyes”, Ed. M. Matsuoka, Plenum, N.Y. 1990, “Topics in AppliedChemistry: The Chemistry and Application of Dyes”, Waring et al.,Plenum, N.Y., 1990, “Handbook of Fluorescent Probes and ResearchChemicals”, Haugland, Molecular Probes Inc, 1996, DE-A-4445065,DE-A-4326466, JP-A-3/228046, Narayanan et al., J. Org. Chem. 60:2391-2395 (1995), Lipowska et al., Heterocyclic Comm. 1:427-430 (1995),Fabian et al., Chem. Rev. 92: 1197 (1992), WO96/23525, Strekowska etal., J. Org. Chem. 57: 4578-4580 (1992), WO (Axis) and WO96/17628,Chromophores with targeting properties are preferred. Targetingproperties of chromophores can be achieved by conjugation ofchromophores to targeting molecules such as peptides, antibodies orother synthetic proteins.

The use of active substances biosynthentically forming chromophores orfluorophores after administration of the active substances is subjectmatter of the invention. 5-aminolaevulin acid (5-ALA) and ester of 5-ALAare mentioned to be preferred.

LSCM consisting of particulate or vesicular polymers containing,transporting and releasing air or fluorinated gases (e.g. SF6 orperfluorinated alkanes with 1-6 atoms or other gases as described inWO97/29783) are subject matter of the invention. Particulate polymerscoupled to target-searching peptides or protein are particularlypreferred.

LSCM containing radionuclides are subject matter of the invention.Radionuclides are both non-metal nuclides and metal nuclides, each forSPECT (single photon emission computed tomography) or PET (positronemission tomography) technique.

Non-metal nuclides are covalently bound to carbons of chemicalstructures. A particularly preferred non-metal nuclide is radioactiveiodine (SPECT: ¹²⁵I, ¹²³I, ¹³¹I; PET: ¹²⁴I) or carbon ¹¹C (PET).

Metal radionuclides are preferably ⁹⁰Y, ^(99m)Tc, ¹¹¹In, ⁴⁷Sc, ⁶⁷Ga,⁵¹Cr, ^(177m)Sn, ⁶⁷Cu, ¹⁶⁷Tm, ⁹⁷Ru, ¹⁸⁸Re, ¹⁷⁷Lu, ¹⁹⁹Au, ²⁰³Pb and ¹⁴¹Ce(for SPECT) and ⁸⁶Y, ^(94m)Tc, ^(11Om) _(In), ⁶⁸Ga, ⁶⁴Cu (for PET).These are bound by complex forming substances or radiochelators.

Chelators for metal nuclides are structures with donor atoms such as N,S, O, which bind metals in an appropriate spatial arrangement and form acyclic metal complex or chelates. These are, in particular, N³S, N₂S₂systems on the basis of aminoalkyl, thioalkyl, aminocarbonyl,thiocarbonyl structure elements (Kirk-Othmer Encyclopedia of ChemicalTechnology, Vol. 5, 339-368).

Chelates on the basis of N₃S and N₂S₂ are described, for example, inU.S. Pat. Nos. 4,444,690; 4,670,545; 4,673,562; 4,897,255; 4,965,392;4,980,147; 4,988,496; 5,021,556 and 5,075,099, WO92/08494.Representative chelators are further described in U.S. Pat. No.5,559,214 A, WO 95/26754, WO 94/08624, WO 94/09056, WO 94/29333, WO94/08624, WO 94/08629 A1, WO 94/13327 A1 and WO 94/12216 A1; WO89/00557,U.S. Pat. Nos. 4,647,447; 5,367,080; 5,364,613. Chelates are alsomodified proteins binding e.g. ^(99m)Tc (U.S. Pat. No. 5,078,985).

Chelate structures are selected from macrocyclic or open-chainaminocarboxylic acids. Macrocyclic chelator groups are preferablytetraazacyclododecane chelates, such as1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA);1,4,7,10-tetraazacyclododecan-N,N′N″-triacetic-acid (DO3A);1-Oxa-4,7,10-triazacyclododecane-N,N′,N″-triacetic acid (OTTA) as wellas dibenzo[18]crown-6,(CH₃)₆[14]-4,11]-dien-N4, and (2.2.2-cryptate).Open-chain amino carboxylic acids are, for example,trans(1,2)-cyclohexano-diethylentriamine pentaacetic acid (CDTPA) andanalogues thereof, N,N,N′,N″,N″-diethylenetriamine pentaacetic acid(DTPA), ethylenediamine tetraacetic acid (EDTA),N-(2-hydroxy)-ethylenediamine triacetic acid, nitrilo triacetic acid,N,N-di-(2-hydroxyethyi)-glycine, ethylenbis-(hydroxyphenylglycine) aswell as their derivatives by chemical substitution at the ethyleneand/or acetic acid residues. Further derivatives are DTPA-BMA, DPDP, TMTand HPDO3A.

Furthermore, chelate structures are selected from the substance classesof the polyphosphates, such as e.g. sodiumtripolyphosphate andhexametaphosphoric acid; 1,3-diketones, e.g. acetyl acetone,trifluoracetyl acetone, thenoyltrifluoracetone; hydroxy carbonic acid,e.g. lactic acid, citric acid, gluconic acid, and 5-sufosalicyl acid;polyamines, e.g. ethylenediamine, diethylentriamine,triethylentetraamine, triaminotriethylamine; aminoalcohols, e.g.triethanolamine and N-(2-hydroxyethyl)-ethylendiamine; aromaticheterocyclic bases, e.g. 2,2′-diimidazol, picolinamine, dipicolinamine,1,10-phenanthrolin; phenols, e.g. salicylaldehyde, disulfopyrocatechol;aminophenoles, e.g. 8-hydroxychinolin oxime sulfonic acid; oximes, e.g.dimethylglyoxime, salicylaldoxime; peptide with chelating end groups,e.g. polycystein, polyhistidine, polyasparagine acid, polyglutamineacid, glycine-glycine-cysteine, or combinations of amino acids of thatkind; Schiff's bases, e.g. disalicylaldehyde, 1,2-Propylendiime; tetrapyrrole, e.g. porphyrins, tetraphenylporphyrines, benzoporphyrins,chlorines, tetraphenylchlorins, benzochlorins, bacteriochlorins,pheophorbides; purpurinimides, expanded tetra- and pentapyrroles(texaphyrins); sulphur compounds, e.g. toluendithiol,Meto-2,3-dimercaptosuccinic acid, dimercaptopropanol, sodiumdiethyldithiocarbamate, dithizone, diethyldithiophosphoric acid,thiourea; phosphonic acids, e.g., nitrilotrimethylenphosphonic acid),ethylenediamine-tetra(methylenephosphonic acid), hydroxyethylidendiphosphonic acid, or combinations of 2 or more of the structuresmentioned.

Complex forming structures for ^(99m)Tc are furthermore^(99m)Tc(I)(H₂O)₃(CO)₃ ⁺ from which the ^(99m)Tc tricarbonyl complexwith amino carbonic acids or other chelating donor atoms is formed.

Chelator structures and complex forming substances are bound to carrier,vector, targeting or transporter molecules such as e.g. polymers,proteins, peptides, antibodies, oligonucleotides, polysaccharides andcombinations and derivatives thereof, via linkers. In this context,chelator structures and complex forming substances are linked by meansof functional groups of the chelator backbone, by means ofderivatisation of donor groups into derivatised donor groups such ase.g. acids into amides, alcohols into ethers, thioles into thioethers,or by means of free coordination sites of the metal. The coupling tocarrier, vector, targeting or transporter molecules can take place inmolar ratios of 1 to 100. Linker and derivatives for chelators aredescribed in WO94/08629, WO94/09056, WO96/20754.

Preferred structures are ^(99m)Tc-Medronat, ^(9am)Tc-Sestamibi,^(99m)Tc-ECD, ^(99m)Tc-MAG3, ¹¹¹In-DTPY-octreotide,¹¹¹In-DTPA-octreotate, ¹⁸F-fluordesoxygiucose (FDG), ¹⁸F-dopamine,¹⁸F-L-DOPA, ¹⁸F-fluorcholine, ¹⁸F-fluormethylethylcholin,¹⁸F-fluordihydro-testosterone, ⁶⁸Ga-NODAGATOC, ⁶⁸Ga-DOTYTOC.

LSCM exhibiting an absorption of X-rays are subject matter of theinvention, in particular triiodated aroma substances and complexes withlanthanoid ions La, Ce, Pr, Nd, Pm, Sm, Eu1 Gcl1 Tb, Dy, Ho, Er, Tm, Yb,and Lu, Eu, Tb, Yb, preferably Gd, Tb, Dy, Ho, as well as structurescontaining the triiodated aroma substances and complexes with lanthanoidions.

A particular advantage of the combination of ECCM and LSCM according tothe invention is the possibility of using high-resolution imaging. Withuse of ECCM alone, the use of high-resolution imaging was not possible,since the measure intervals available are very short. However, thecombination of ECCM and LSCM according to the invention makes itpossible to use high-resolution imaging to obtain specific morphologicalinformation.

During any imaging methods, the assessment of exact morphologicaldetails depends on a high spatial resolution, in order to obtainhigh-resolution images, however, a longer examination period isnecessary. Moreover, measuring methods have to be applied which areunsuitable for the synthetic imaging of the ECCM, since an increase ofthe spatial resolution leads to a significant increase of the measuringtime and a reduction of the ratio of signal and noise. Furthermore,high-resolution measuring methods are unsuitable for obtaining rapidchanges in the distribution of the contrast agent, as necessary for therapid distribution of ECCM.

The individual components of the combination of ECCM and LSCM accordingto the invention can be imaging contrasting agents or signallingsubstances for synthetic imaging methods (monomodal) or multiple(polymodal, multimodal) imaging methods.

The monomodal methods can be selected from the group comprising: MRT,PET, CT, optical imaging, ultrasound, SPECT, X-ray.

Synthetic imaging methods which are appropriate for the illustration ofcombinations of ECCM and LSCM are fusion methods of different imagingmethods such as PET-CT, PET-MRI, PET-optical imaging, MRI-CT₁ ultrasoundoptical imaging, PET-SPECT, SPECT-CT, MRT-optical imaging and SPECT-MRT.

For the use of a combination according to the invention, which isillustrated by means of polymodal methods, devices and software are usedwhich visualise the signals of the individual components separately asto space and time and which carry out an automatic comparison of thespatial and temporal signal intensities for each suspect lesion orsuspect area.

With monomodal application of the combination of the invention, first,for example, the ECCM is applied and then, following with a time delay,the LSCM is applied. The time interval between the application of theECCM and the LSCM is determined in such a way that the application ofLSCM only takes place when the blood level of ECCM has sunk to a lowlevel and no longer interferes with the subsequent application of theLSCM. In that way, the signals of the imaging agents cannot overlap andinfluence each other. Since the ECCM has fallen to such low level onlyten minutes after application, the subsequent application must becarried out with a delay.

In case the combination of ECCM and LSCM according to the invention arevisualised by means of polymodal synthetic imaging, the ECCM and theLSCM can also be applied simultaneously or with a very small delay. Byusing different synthetic 15 imaging methods, overlap of the individualsignalling components is avoided. The signalling components of the ECCMand the LSCM can be visualised separately. The almost simultaneousapplication is appropriate, above all, if radioisotopes with a shortdecay time are used. This applies, e.g. if ^(1B)F-based PET tracer arecombined with the MRI ECCM Gd-DTPA.

Thus, the combination of ECCM and LSCM is the subject matter of thepresent invention when used as:

-   -   monomodal time-delayed application, e.g. monomodal measurement        0-15 minutes after injection of the ECCM and second measurement        15 minutes to 24 hours after injection of the LSCM    -   polymodal time-delayed application    -   polymodal simultaneous application

The time-delayed application of the individual components of thecombination can be achieved by different devices. The combinationaccording to the invention can be carried out by two-chamber ormultiple-chamber syringes or cartridges. A further device for theadministration of the combination according to the invention is a devicefor carrying out the time-controlled application of the individualcomponents. Hereby, the time control is carried out in correspondencewith the application regimen for the LSCM and ECCM as described for themethod of the present invention.

Thus, subject matter of the present invention is an application devicefor the combined application of an extracellular contrast agent (ECCM)for the diagnosis of lesions in combination/connection with alesion-specific contrast agent (LSCM), wherein the application devicehas at least two chambers or receptacles for the separate absorption andapplication of the ECCM and the LSCM.

Said application device can be a two-chamber or multiple-chambersyringe, it can also be a two-chamber or multiple-chamber cartridge.Furthermore, an apparatus comprising two distinct chambers containing anLSCM and an ECCM, respectively, wherein the release of contrast agent iscontrolled with an individual pump for each chamber, and wherein theoutlets of the two chambers are fitted with tubing which is connected bya Y-piece which ends in a single tube so that both contrast agents areapplied to the patient via this single tube may be used as applicationdevice.

Furthermore, an embodiment of the present invention is the use of anapplication device for the administration of an LSCM and an ECCM to asubject or patient, whereby the application regimen for the LSCM andECCM is as described for the method of the present invention.

EXAMPLES Example 1

A middle-aged patient. This patient suffered from a malignant braintumour, a glioblastoma, and was treated for it. Apart from an operation,the treatment also included radiotherapy of the brain with increasedradiation in the former operation area using directed stereotactictechniques. After about six months, the patient's initially goodclinical situation deteriorated. The clinical examination results inpresumed tumour growth recurring.

Diagnostic imaging by means of a PET-CT device combination canillustrate tumours both by using X-ray contrast agents and by using PETisotopes. With an extracellular CT contrast agent such as e.g.Ultravist® a region accumulating contrast agent inhomogeneously in theregion of the former tumour bed can be seen. With regard to differentialdiagnosis, apart from a tumour recurring—a local relapse—, cell deathcaused by high radiation—radionecrosis—is possible.

The PET isotope ¹⁸F-fluordeoxyglucose (FDG) as LSCM, which was injectedsimultaneously, provides the explanation for the differential diagnosis:the missing concentration of the LSCM in the cells of the region, which,in the CT, had shown a concentration of ECCM, proves the presence ofradionecrosis. Further therapy consists in the administration ofcorticoids; the patient's prognosis is clearly better than in the caseof a local relapse being present.

Example 2

A patient, typically between 50 and 70 years of age, is admitted tohospital for further diagnosis and therapy due to blood deposits in thestool. The coloscopy carried out showed a malign tumour of the colon.During the ultrasound scan of the liver, which was also carried out, anindividual, defined focus was found in the right hepatic lobe which leadto the presumption of a metastasis in the liver, a liver metastasis.

The magnetoresonance tomography which was carried out, first, with anextracellular contrast agent (EECM, e.g. Magnevist®), then directlyfollowed by a lesion-specific contrast agent (LSCM, e.g. Resovist®),confirmed, in the first step, the presence of a liver focus in the righthepatic lobe by means of ECCM. Differentiation of the type of tumour,however, is not possible. In this case, only the accumulation of thetumour with the LSCM showed that the cells of this dimension are livercells and not tumour cells. Thus, metastasis of the colon tumour couldbe excluded, the diagnosis of a benign simple hemangioma of the livercould be secured by the combined contrast agents examination. Thepatient is subjected to a normal tumour operation of the colon.

Example 3

A patient, typically in his late 50s or early 60s with a history of arecent heart attack is now being investigated for viable myocardiumbefore cardiac bypass surgery. The patient's history includes a lowgrade nicotine abuse 20 years ago with overall eight pack-years exposureand a history of tuberculosis during adolescence. Previous diagnosticcoronary angiography has revealed stenoses in the coronary arteries. PETimaging with use of F¹⁸-FDG as radiotracer revealed viable myocardiumwith the possibility to improve cardiac function with arevascularization procedure. Coincidentally an increased tracer uptakewas seen during cardiac PET imaging in the left upper lobe of the lung,being consistent with cancer or infectious disease.

A targeted contrast enhanced high-resolution thin slice computedtomography scan was performed in the upper lung lobes showing a wellenhancing, approximately 2 cm measuring lesion. The high resolution thinslice images clearly showed a solid appearance of the tumor and verythin streaky structures surrounding the tumor in a radiate appearance,being typical for spiculae of a lung cancer. The combination of contrastenhancement in the solid lesion and the speculated appearance of thetumor secured the diagnosis of a small lung cancer.

The entire disclosure of all applications, patents and publications,cited herein and of corresponding application No. 07110922.7 EP, filedJun. 22, 2007, and PCT/EP2008/057886, filed Dec. 22, 2008, areincorporated by reference herein.

The invention claimed is:
 1. A polymodal method for imaging a lesion ina patient comprising: administering to said patient: an extracellularcontrast medium (ECCM) comprising gadolinium-DTPA, and a lesion-specificcontrast medium (LSCM) different from the ECCM, which is enriched in thelesion 10 minutes after administration to said patient and is retainedin the lesion for at least 1 hour, wherein the LSCM is¹⁸F-fluorodesoxyglucose (FDG), ¹⁸F-dopamine, ¹⁸F-L-DOPA,¹⁸F-fluorocholine, ¹⁸F-fluoromethylethylcholine, or¹⁸F-fluorodihydrotestosterone subjecting the patient to polymodalimaging wherein at least two different imaging modalities are used toprovide at least two different imaging signals which are immediatelyinterpolated by a fusion method of the at least two different imagingmodalities and wherein the ECCM and LSCM are applied at the same time orthe LSCM is applied with a short time delay of 30 minutes maximum afterthe ECCM.
 2. The method of claim 1, wherein the polymodal imaging usesone of the following combination of imaging modalities: MRI imaging and¹⁸F-PET tracer imaging; MRI imaging and CT imaging; MRT-optical imagingand SPECT-MRT imaging.
 3. The method of claim 1, wherein the polymodalimaging combines MRI imaging and ¹⁸F-PET tracer imaging modalities. 4.The method of claim 1, wherein the ECCM and the LSCM are administered tosaid patient consecutively with a time delay between administrations of10 to 30 minutes.
 5. The method of claim 1, wherein the ECCM and theLSCM are administered to said patient consecutively with a time delaybetween administrations of 10 to 15 minutes.
 6. The method of claim 1,wherein the ECCM and LSCM are administered consecutively.
 7. The methodof claim 1, wherein the ECCM and LSCM are administered simultaneously.8. The method of claim 1, wherein the LSCM is ¹⁸F-fluorodesoxyglucose(FDG).
 9. The method of claim 1, wherein the LSCM is¹⁸F-fluorodesoxyglucose (FDG) and the ECCM is gadopentetaticacid/dimeglumine salt.
 10. The method of claim 1, wherein the ECCMcomprises gadopentetatic acid/dimeglumine salt and the LSCM comprises a¹⁸F-based PET tracer selected from the group comprising¹⁸F-fluorodesoxyglucose (FDG), ¹⁸F-dopamine, ¹⁸F-L-DOPA,¹⁸F-fluorocholine, ¹⁸F-fluoromethylethylcholin and¹⁸F-fluorodihydrotestosterone.
 11. A kit for conducting a polymodalmethod for imaging a lesion in a patient comprising: an extracellularcontrast medium (ECCM) comprising gadolinium-DTPA, and a lesion-specificcontrast medium (LSCM) different from the ECCM, which is enriched in thelesion 10 minutes after administration to said patient and is retainedin the lesion for at least 1 hour, wherein the LSCM is¹⁸F-fluorodesoxyglucose (FDG), ¹⁸F-dopamine, ¹⁸F-L-DOPA,¹⁸F-fluorocholine, ¹⁸F-fluoromethylethylcholine, or¹⁸F-fluorodihydrotestosterone, subjecting the patient to polymodalimaging wherein at least two different imaging modalities are used toprovide at least two different imaging signals which are immediatelyinterpolated by a fusion method of the at least two different imagingmodalities and wherein the ECCM and LSCM are applied at the same time orthe LSCM is applied with a short time delay of 30 minutes maximum afterthe ECCM, wherein the kit is provided in a form suitable forsimultaneous or consecutive administration of the ECCM and the LSCM tosaid patient.
 12. The kit of claim 11, wherein said ECCM isgadopentetatic acid/dimeglumine salt.
 13. The kit of claim 11, whereinthe LSCM is ¹⁸F-fluorodesoxyglucose (FDG).
 14. The kit of claim 11,wherein the LSCM is ¹⁸F-fluorodesoxyglucose (FDG) and the ECCM isgadopentetatic acid/dimeglumine salt.
 15. A polymodal method for imaginga lesion in a patient comprising: administering to said patient: anextracellular contrast medium (ECCM) comprising gadolinium-DTPA, and alesion-specific contrast medium (LSCM) selected from: ^(99m)Tc-Medronat,^(99m)Tc-Sestamibi, ^(99m)Tc-ECD, ^(99m)Tc-MAG3, ¹¹¹In-DTPY-octreotide,¹¹¹In-DTPA-octreotate, ¹⁸F-fluorodesoxyglucose (FDG), ¹⁸F-dopamine,¹⁸F-L-DOPA, ¹⁸F-fluorocholine, ¹⁸F-fluoromethylethylcholine,¹⁸F-fluorodihydrotestosterone, ⁶⁸Ga-NODAGATOC, or ⁶⁸Ga-DOTYTOC; which isenriched in the lesion 10 minutes after administration to said patientand is retained in the lesion for at least 1 hour, and subjecting thepatient to polymodal imaging wherein at least the two different imagingmodalities of PET-MRI imaging and SPECT-MRT imaging and are used toprovide at least two different imaging signals which are immediatelyinterpolated by a fusion method of the at least two different imagingmodalities and wherein the ECCM and LSCM are administered sequentiallyor simultaneously.
 16. The method of claim 15, wherein the ECCM and theLSCM are administered to said patient sequentially with a time delaybetween administrations of 10 to 15 minutes.
 17. The method of claim 15,wherein the ECCM and the LSCM are administered to said patientsimultaneously or the LSCM is applied with a short time delay of 30minutes maximum after the ECCM.